Focal therapy with high-intensity focused ultrasound is effective in the medium term and rarely causes urinary or rectal side effects in patients with clinically significant localized prostate cancer, a large, multicenter study shows.
The study, “A Multicentre Study of 5-year Outcomes Following Focal Therapy in Treating Clinically Significant Nonmetastatic Prostate Cancer,” was published in the journal European Urology.
High-intensity focused ultrasound (HIFU) is a new prostate cancer treatment technology, cleared by the U.S. Food and Drug Administration in 2015, that involves the use of high-frequency ultrasound waves to heat and destroy cancer cells in the prostate, leaving the surrounding tissue unharmed.
As opposed to performing radiotherapy, surgery, or cryotherapy on the entire prostate gland, HIFU specifically targets only the area containing the tumor, minimizing the chances of damage to surrounding tissues and reducing the probability of side effects such as erectile dysfunction or urinary incontinence. In addition, it also shortens hospital stays.
This makes HIFU an appealing treatment option for men whose cancer is limited to the prostate and has not spread to other regions in the body.
Despite its potential, studies evaluating the effectiveness and safety of the technique were small, had a short follow-up, or only addressed patients with low-risk disease.
Therefore, researchers conducted a larger prospective study to examine the outcomes and secondary effects of HIFU treatment for prostate cancer over a period of five years.
The study enrolled 625 patients with clinically significant nonmetastatic prostate cancer who had undergone HIFU using a Sonablate 500 device at one of nine secondary care centers in the U.K. The median follow-up time was 56 months, or 4.7 years.
Before the HIFU treatment, the tumors were localized using multiparametric magnetic resonance imaging (mpMRI) combined with prostate biopsies.
Five years after the focal therapy, most patients — 88% — were alive and failure-free, meaning they did not have any radical or systemic therapy and their cancer had not metastasized, or spread.
Nearly all the patients — 98% — survived without their cancer metastasizing. There were seven deaths, but none were attributed to prostate cancer.
Eight patients switched to salvage radical prostatectomy, 36 had salvage external beam radiotherapy, and one received androgen deprivation therapy.
HIFU was repeated in a small portion of the patients, 121 in total, up to two times, with most repeating the procedure just once, if the cancer was still present or reappeared.
Complications from HIFU were rare. In the six months following the procedure, urinary tract infections were the most prevalent, affecting 8.5% of the patients.
Between two and three years after the procedure, only 2% had developed urinary incontinence that required the use of a single daily pad, but all patients could continue their daily routines with no major difficulties.
Bowel problems were even more rare, occurring in 0.3% of patients, including two cases of rectourethral fistula, which is a fissure between the rectum and urethra. Erectile dysfunction was not possible to analyze.
“On the basis of our data, patients currently diagnosed with prostate cancer that is suitable for focal therapy may prefer to have the option to choose whole-gland radical therapy or focal therapy,” the researchers wrote.
They also add that it may be unfeasible to perform larger, longer, and randomized studies to compare the outcomes of focal therapy with radical therapy, given the long natural course of prostate cancer, but they cite as examples prostate brachytherapy (a form of radiation therapy) and robotic prostatectomy, which were approved for clinical use without or before the completion of randomized clinical trials.
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